To effectively make use of a heat source such as waste heat, biomass, and heat and cold is to solve an environmental problem and an energy problem. A Stirling engine has features that the engine does not select a heat source and the engine can be operated if there is a temperature difference. Therefore, the Stirling engine is suitable for effectively making use of the heat source.
Attention is paid to heat recovery from exhaust gas flowing through a flue as utilization of waste heat, and a Stirling engine suitable for installation of such a flue is proposed (non-patent document 1).
According to non-patent document 1, a heating portion disposed in the flue includes U-shaped tubes laterally arranged in a row. Combustion gas is made to flow perpendicularly to a direction of the row of the U-shaped tubes which function as heaters, thereby uniformizing a heater temperature distribution.
The present inventors figured out the heating portion shown in FIG. 13 by reference to non-patent document 1.
FIG. 13 is a perspective view of an essential portion showing a configuration of the heating portion of the Stirling engine.
As shown in FIG. 13, as the heating portion of the Stirling engine, U-shaped tubes 101, 102, 103, 104 and 105 having difference sizes and similar shapes are disposed on the same plane, and the U-shaped tubes 101, 102, 103, 104 and 105 are laterally arranged in a row. The heating portion shown in FIG. 13 makes combustion gas to flow perpendicularly to a direction of the row of the U-shaped tubes like non-patent document 1 as shown with arrows in FIG. 13. When a pressure loss of exhaust gas at the heating portion of the U-shaped tube does not cause a problem, exhaust gas is made to flow in parallel to the direction of the in the row, more combustion gas is brought into contact with the U-shaped tubes to increase a heat-transfer area, and an amount of heat taken from the heating portion into the engine may be enhanced.